Brake pad query

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Got new pads put on my gf's 02 Golf.

The pads seem to be wedge shaped. As in only part of the pad is touching the disc. I would have thought the entire flat pad surface area should be touching the disc.
Is this normal?

I ask because the brakes seem to have lost their firm feel. (although this could be another issue)

DublinDilbert

Ummm sounds funny.... can you take a picture and show us what it looks like?

bazz26

If in doubt bring them back to the place that fitted them and ask the fitter if they are ok.

It is not uncommon for a slightly incorrect brake pad to be fitted especially when they are spuerious parts.

niceirishfella

+1
Ask for the "contact area" to be checked - looks like the pads ain't contacting the disc - dangerous if its the case.

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http://img525.imageshack.us/i/img2816s.jpg/

stratos

Could it be that it's the disc that is worn. Most discs wear conically as the outer part of of the disc is moving faster than the inner part and wear is always uneven. The last time I fitted pads to my car I noticed this and on inspection the discs were so worn I replaced them.
The outer surface of the disc does most of the work as you move inwards the disc is moving slower in relation if you know what i mean. For example the discs I took out had a bout a 2 to 3 mm lip on the outer part of the disc but the inner part just about had a discernable step.

I don't know what the tolerances are and maybe the pads just need to bed in which they should do fairly quickly. I have never seen wedge shaped pads.

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Apologies for the size. Stopid computer!

Tails142

I think that's just the chamfered edge on the edge of the pad, further in on the pad, say an inch from the edge, the whole area would be touching.

Seth Brundle

Is it just me or is the shoulder for the disk (the bit on the hub) odd looking?

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Yeah but as it is now, when I apply the brake only a 1cm section is contacting the disc instead of the 3cm that should.

stratos

That looks very odd. Is it just the picture or does that disc look very worn with a large visible lip. The pad looks like an old one in the wrong way around but i doubt thats possible. odd. The last time I saw something like that was when new discs had been fitted and the old pads reused not a great idea.

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Eh I think that lip is just an outer metal cover that protects the disc from dirt etc.

stratos

Yes i think the lip is just the stone guard, is it possible new discs were fitted and they reused the old pads. it's all I can think of.

Seth Brundle

The lip does look huge on them -they may well need to be replaced (replace both sides at the one time).

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Here's another pic



No only the pads were changed.

Seth Brundle

Is that the same caliper (upsidedown) or the other side?

Are the disc(s) badly warped?

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Its the other side.

No the discs seem fine. Have had the car for a few years and never been a issue with them.

Btw there was no problem with the car until the new discs were put on.

stratos

That pad is really wedge shaped I have never seen one with that amount of angular wear or shape. I would imagine that would put a lot of localised heat into the disc and possibly warp it, braking would be reduced too as the only the inner slower part of the disc is contacted. We need a brake expert here.

greglo23

Most modern brake pads are shaped like that. Its perfectly normal. After a few days the normal feel will come back to the pedal as well.

alo1587

greglo23 wrote: »

Most modern brake pads are shaped like that. Its perfectly normal. After a few days the normal feel will come back to the pedal as well.

+1,the chamfered edge helps the pad to bed in better if the disc has a lip on it.New pads always feel fairly ****e,they need time to bed in.Avoid braking hard for the first hundred miles or so

Anan1

To my uneducated eye it looks as though the discs are in dire need of replacement and the pads are the wrong ones for the car. Mind you, does any car have pads that contact the disc at an angle? Because that's the only way I can see those pads as working.

2 stroke

Thats not normal and looks dangerous. Dont drive until you get it checked.

alo1587

2 stroke wrote: »

Thats not normal and looks dangerous. Dont drive until you get it checked.

Its normal i can assure you.Example here..

http://www.topbrakes.com/images/hawk_pads_technology_big.jpg

stratos

Here is a picture of a new brake pad for my car. As you can see it is quite square and has a lot of meat on it. ( sorry about the carpet)

Midnight_EG

Just remember not everyone has the same brakes.....

A mechanic told me why the wedge shape is what it is, but i forget now :[

Once I remember I'll come back and edit :L

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I understand having slightly chamfered pads to help reduce brake squeal but this is taking the piss.

This chamfered pad below still has a large surface area in contact unlike teh one on my gf's Golf!

stratos

I very much doubt thats normal.

alo1587

Different brake pad manufacturers might just have different reasons for more or less of a chamfer angle.If you are worried about it i suggest you go back to the mechanic that fitted them.He'll probably laugh at you though..

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Okay well time for the rest of the story.

After said mechanic fitted the new pads I took the car for a drive and noticed the brakes quite unresponsive. i.e. my foot was to the floor nearly before the brakes worked.
Went back and told him this. He said they take time to bed in but in case of any air in the lines he will bleed it again.
He did so and no change. Brakes still piss poor. Worse than before the change!:rolleyes:

He proceeds to bled it again thinking its just trapped air in the lines but to no avail. No leaks visible on the brakes either so he deduce that possibly the master cylinder is fooked.:(

Some days later after ordering the incorrect master cylinder he fits the new correct master cylinder. Bleeds the lines and adds new dot 4.
Surprise surprise there's still no improvement. The brake pedal has too much movement and brakes still seem spongy.

He then agrees to get the brake callipers reconditioned in case the seals are gone.
Few days later he re-fits the callipers and still no improvement!! :eek:

So the car is unsafe to drive leaving us stranded and he has no idea as to what it could be!

stratos

Something is badly wrong here I think. If you pushed the pedal hard those pads would tilt into the disc causing the caliper piston to do the same and maybe jam in the caliper bore. It's gotta be wrong or worn pads.

alo1587

Did the brakes feel spongy before getting the new pads fitted or were they ok?

EPM

They look exactly like the pads on my car to be honest after they were changed and I've never had an issue. The lip is the stone shield on most VAG cars. If it was me OP, I'd just get the car to another garage and let them to sort it maybe

EDIT - I'll try get a pic of mine later if it helps

Mr.David

Those pads look strange alright. There must be the best part of 10mm difference between top and bottom thickness? Looks like the die used to make the pad didnt fill fully or something - is it the same on the other side? Yes, chamfers are used for NVH reasons in particular to combat squeal but thats taking the piss. The effective pad area is about the same as that on a bicycle.

Mr.Diagnostic

The pad shape is normal. There is more surface sitting flush with the disk that it would appear in your pics. If you ask in any motor factors they will show you a pad and you will see what I mean.

The problem with the brakes is really very basic and easily diagnosed. The mechanic should have been able to do this. Bring it to someone else.

niceirishfella

Mr.Diagnostic wrote: »

The pad shape is normal. There is more surface sitting flush with the disk that it would appear in your pics. If you ask in any motor factors they will show you a pad and you will see what I mean.

The problem with the brakes is really very basic and easily diagnosed. The mechanic should have been able to do this. Bring it to someone else.

+1
Your mechanic's a DingBat.
2nd opinion required - and I've seen worse lips on discs.

alo1587

Thanks Mr.Diagnostic for backing me up on the pad shape:D If the brake pedal still feels spongy after all the work the mechanic has done,i'd bring it to a mechanic that knows what he's doing.Sounds like there's still air in the brake lines.Does he know how to bleed brakes??

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Okay im convinced that the brake pad shape is normal. Cheers lads.

Yeah this guy does lots of brake pad changes especially on VW's so I imagine he knows how to bleed lines at this stage.

I'll pop it into another garage. Are the likes of quickfit,fastfit, or advance pitstop worth going to see?

ianobrien

Somebody might know, but does the car have a load compensating valve on the brake lines to the back wheels?

If the car does, it can not be bled with the suspension unloaded (or the car jacked up). Most manufacturers have guidelines on how to bleed brakes if they have load valves.

I remember crawling (and it was some struggle as I'm not small!) under the back of an AX to bleed the back brakes, and we couldn't jack the car because of them valves.

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Latest theory is that air could be trapped in the ABS unit. Requires hooking up to a diagnostics machine.
Its booked in with a VW dealership for servicing next week.

vw4life

them pads look normal,how many miles have you driven on the new pads and the pedal will feel spongey until the new pads bed in correctly and your discs look fine too.

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Driven about 10 miles on them without any improvement. I know what new pads feel like before they bed in and this aint the problem.

It shouldnt be a case of the pedal being to the floor before any braking occurs.

Lenny

View Profile wrote: »

Okay well time for the rest of the story.

After said mechanic fitted the new pads I took the car for a drive and noticed the brakes quite unresponsive. i.e. my foot was to the floor nearly before the brakes worked.
Went back and told him this. He said they take time to bed in but in case of any air in the lines he will bleed it again.
He did so and no change. Brakes still piss poor. Worse than before the change!:rolleyes:

He proceeds to bled it again thinking its just trapped air in the lines but to no avail. No leaks visible on the brakes either so he deduce that possibly the master cylinder is fooked.:(

Some days later after ordering the incorrect master cylinder he fits the new correct master cylinder. Bleeds the lines and adds new dot 4.
Surprise surprise there's still no improvement. The brake pedal has too much movement and brakes still seem spongy.

He then agrees to get the brake callipers reconditioned in case the seals are gone.
Few days later he re-fits the callipers and still no improvement!! :eek:

So the car is unsafe to drive leaving us stranded and he has no idea as to what it could be!

So how much has this set up back already?
all cars are different, how about you pop down to a motor factors and ask to see a set of pads for the model of your car? see how they're
pads dont always be a flat surface, this is so the pads can wear in even. you're not ment to brake "sharply" on new pads for 200 miles, this will give them time to even out.I find it hard to believe that if they were the wrong pads for the car that they'd fit into the caliper. what year is this golf btw?

Busta Hyman

not trying to be argumentative but are you guys kidding me with the that looks normal posts?. the camfered edges on the pad are at the leading / trailing edges of the pad IN THE DIRECTION OF ROTATION! those pads are cambered from the hub to the lip.there extremely dangerous imo. on pads with the camber on them the center part of the pad will make full contact with the disk from the start. the bedding in process works as the pats and disk meld together not as the pad wears in to get a full brakeing surface across the pad. OP get that car VERY VERY slowly to a reputable garage Or get an AA inspection done on the work thats an accident waiting to happen

vw4life

Busta Hyman wrote: »

not trying to be argumentative but are you guys kidding me with the that looks normal posts?. the camfered edges on the pad are at the leading / trailing edges of the pad IN THE DIRECTION OF ROTATION! those pads are cambered from the hub to the lip.there extremely dangerous imo. on pads with the camber on them the center part of the pad will make full contact with the disk from the start. the bedding in process works as the pats and disk meld together not as the pad wears in to get a full brakeing surface across the pad. OP get that car VERY VERY slowly to a reputable garage Or get an AA inspection done on the work thats an accident waiting to happen

thats what the pads look like when fitted,if you seen them off the car you'd see that its only that corner of the pad thats chamfered

Busta Hyman

i hope thats the case i was under the impression it would be like the diagram that was linked earlier in the post i.e from leading edge to 1/3 of the pad not from hub to rim when mounted? but anyway if the brakes feel spongey and they only went in for a pad change and its taken a few bits of work id guess theres a possibility the guy fitting them fekked up somewhere

Voodoomelon

Seems bizarre to me that he did all that work diagnosing, without changing out the pads first.

alo1587

Voodoomelon wrote: »

Seems bizarre to me that he did all that work diagnosing, without changing out the pads first.

+1,i would have put back in the old pads and driven it before doing anymore.Its possible that he didnt slightly file down the outer circumference of the pad,if there's a lip on the outer edge of the disc.This causes the pad not to seat fully on the disc surface and the brakes willfeel spongy.I usually do that when fitting pads if the pad edge is touching the lip (and the owner is too tight to get new discs!).
Were the brakes spongy before you went in to get the pads changed or were they ok?

blahblah06

lo lad. same thing happened to me. there is two different types of pads for the golfs. after mine been replaced we had to get the abs unit replaced at a cost of 800 euro. google it. its notorious specially if u have any warning lights

mickdw

Ive just seen this thread and the responses here are crazy. The pads are normal, granted some of pics make it look like they are tapered at an odd angle but Im 100% sure they are perfect. Genuine VAG pads have a huge taper allowing approx 60% of full contact area going to 100% contact area when pads have worn down by about
5 to 7mm. This smaller contact area will allow the pad to be into an ridges in the disc etc much more quickly allowing normal pedal feel to return more quickly although a slight reduction in braking performance will be present. The OP needs to drive at least 100 miles on the fresh pads before judging if the pedal is right or wrong. Of course brakes are going to be worse on the new pads for a while. People get the impression that old pads lead to bad brakes when in fact the opposite is true. The old pad is bedded in perfectly and is much thinner leading to excellent brake pedal feel. Unfortunately they have to be replaced as they will wear out finally.
In this case, if no improvement after 100 to 200 miles, it might be a case that mechanic damaged the seals in the master cyliner or the abs unit by forcing the fluid backwards through the system when pushing the piston back to fit the neew pad instea of opening the bleed nipple at the caliper. Also, Master cylinder could be damage due to using too much pedal travel when pumping the brake pedal to get the new pads back against the disc. Its not a good idea use the normally unswept area of the master cylinder as corrosion can be present.